Effects of vitamin C and vitamin D interaction on the performance, immunity, and bone characteristics of commercial broilers

This research was conducted to evaluate the efficacy of supplemental vitamin C (VC) at 0 or 200 mg/kg on the performance of commercial broilers fed vitamin D (VD) levels as per NRC recommendations (200 IU) or as per the levels followed in the commercial vitamin premixes (1,800 IU). The on-farm trial was conducted for 4 wk with Ross broilers using a 2 x 2 factorial design; 726 chicks per treatment made up 3 replicates. The weekly performance data showed greater weight gain in the chicks fed supplemental VC at 200 mg/kg when compared with the unsupplemented group, except during the second week. Significantly higher weight gain was noticed in 200 IU VD-fed chicks over those fed 1,800 IU during first and second weeks and for the overall (0 to 3 wk) study. Significant interactions were observed in weight gains between VC and VD, except during the third week. Bone strength was higher for birds fed the VC-supplemented diet at 200 IU of VD. Weekly serum biochemicals were higher (P = 0.009) for total protein for birds on the VC-supplemented diet only during first week, but serum calcium, phosphorus, and alkaline phosphatase showed no particular trend. Antibody titers to SRBC, cutaneous basophilic hypersensitivity response to phytohemagglutinin-P, and heterophil:lymphocyte ratio did not show any difference within groups given supplemental VC or VD. It could be concluded that the VD levels as suggested by NRC (200 IU) promoted better performance of commercial broilers than 1,800 IU in the present study and that supplementing VC at 200 mg/kg improved the performance under commercial growing conditions.